This application claims priority to Japanese application numbers 2000-74131, 2000-84140, 2000-111234, 2000-199999 and 2000-200000, each of which are incorporated herein by reference.
1. Field of the Invention
The present invention relates to improved power tools.
2. Description of the Related Art
Japanese Laid-open Patent Publication Nos. 7-314344 and No. 10-180643 describe power tools that control the drive source (e.g. a motor) for driving the tool bit in order to improve and stabilize the tightening operation in certain predetermined conditions. This type of power tool has a setting switch disposed on the surface of the housing of the tool and the setting switch permits the operator to set the driving condition. Thus, the drive source can be controlled according to a predetermined condition that is set using the setting switch.
Presently, impact power tools are often used for a variety of operations. For example, a tightening tool adapted to tightening fastening devices (e.g., bolts, nuts, screws, etc.) can be used for a temporary tightening operation, a disassembly operation, and a repairing operation in addition to the usual tightening operation. However, known power tools do not include a setting function that permits the operator to set appropriate condition for these types of operations. Therefore, known power tools cannot be effectively used for such operations.
In addition, because the switch for setting the driving condition is disposed on the surface of the housing, the driving conditions can be freely changed by a variety of people. Thus, the known power tools do not permit the driving conditions to be changed only by an authorized person.
Further, known power tools do not provide means for setting maintenance conditions. Thus, known power tools may be utilized beyond the expected lifetime of one or more components of the power tool and the power tool may break down at an inappropriate time. Thus, a long felt need exists to provide power tools that can provide accurate actual use records and promptly inform the operator if maintenance is recommended or required.
In addition, U.S. Pat. No. 5,289,885 describes an impact wrench that can be used to firmly tighten a threaded object, such as a bolt or a nut. In this type of tightening tool, the torque that is generated depends upon the number of times and the frequency at which the hammer impacts or strikes an anvil. In the ""885 patent, a microphone is utilized to detect the impact sound of the hammer striking the anvil. When the number of the impacts by the hammer on the anvil reaches a predetermined number, the motor stops rotating the hammer. Thus, an appropriate amount of torque is applied to the threaded object by stopping the tightening operation when the predetermined number of impacts has been reached.
It is, accordingly, an object of the present teachings to provide improved power tools.
In one aspect of the present teachings, power tools are taught that can be set to a predetermined driving (operating) condition and the setting is not easily changeable. For example, persons that are not authorized to change the driving condition can not easily change the driving condition. Therefore, power tool operations can be performed more effectively and uniformly without a risk that unauthorized changes will be made. Further, a variety of operations can be set and the additional operations permit the operator to use the power tool more efficiently.
In another aspect of the present teachings, power tools may include a setting means for setting the driving (operating) condition for the driving force for the power tool. Various types of setting means are contemplated, including but not limited to a dial, a keypad, a sound sensor and/or a remote control device. A processor or other control means may be provided to control the drive source (e.g. motor) for the power tool according to the inputted driving condition set using the setting means. The driving condition input using the setting means may be appropriately selected for the particular mode of operation for the power tool.
In another aspect of the present teachings, power tightening tools are taught that may include, for example, a hammer and an anvil. Preferably, the hammer continuously rotates the anvil in low torque situations. However, in high torque situations, the hammer may intermittently strike the anvil in order to rotate the anvil and as a consequence, impact sounds are generated. Because the anvil is coupled to a tool bit, the anvil can apply a relatively large torque to the tool bit. Such power tools are generally known, e.g., as impact wrenches and impact screwdrivers.
In another aspect of the present teachings, power tightening tools are taught that may include, for example, an oil unit. An oil unit may be utilized, for example, in angle socket drivers (also known as right angle drills). In high torque situations, the oil unit generates an oil pulse and thereby rotates a socket with higher torque. The oil pulse generates an impact sound.
Such power tools may also optionally include a sound sensor or other detecting means that detects the impact sound caused by, e.g. the hammer striking the anvil or the oil pulse from the oil unit. The processor or other control means may control the drive source according to the output of the detecting means and the particular driving condition set by the setting means.
Preferably, the sound sensor or other detecting means is provided to convert impact sounds into electric signals. If the sound sensor is capable of converting sound into an electric signal (e.g. a piezoelectric buzzer as discussed below), the detecting means also typically can emit sounds if an appropriate electric signal is inputted to the sensor. Therefore, the sensor can also be utilized to alert the operator to particular operating conditions of the power tool.
In another aspect of the present teachings, power tools may include a sensor or other means for detecting information other than sound and an electric signal may be output by the detecting means. For example, means may be provided for distinguishing the outputted electric signal from an electric signal that is utilized to set the driving conditions. A setting means may be provided to set the driving condition based upon the electric signal when the electric signal is identified as an electric signal for setting the driving condition. The other physical information that may be detected by the detecting means may include for example acceleration, light (infrared rays, ultraviolet rays) and/or radio waves. Thus, the detecting means may include an acceleration sensor and/or a light sensor for light such as infrared and/or a radio wave sensor.
In another aspect of the present teachings, various driving conditions may be set, including but not limited to any condition that may effectively control the operation of the power tool, such as the operating condition (e.g., tightening torque, disassembly operation, auto stop, etc.) or other alternative functions (e.g. battery check, maintenance check, maintenance warning, etc.). In one preferred embodiment, the operating condition may be set using an electric signal generated by the sound sensor instead of using a mechanical switch. If the detecting means detects physical information and outputs an electric signal, the detecting means can output electric signals as well as set the driving conditions. However, the electric signal outputted from the detecting means is preferably distinguished using a distinguishing means (e.g. processor) in order to determine whether the electric signal is intended to set a driving condition or not. Therefore, improper setting of the driving condition due to an electric signal output from the detecting means can be avoided.
In another aspect of the present teachings, power tools also may include a processor or other means for controlling the driving force of the power tool according to the driving condition set by the setting means. Detecting means may also be utilized and may serve to detect the physical information that is used when the control means controls the driving force of tool. Because the detecting means may also detect physical information in order to control the drive source, it is not necessary to provide a separate detecting means.
A starting switch (e.g. a main switch) is preferably provided to actuate the drive source (e.g. a motor). Preferably, the processor or other distinguishing means may be constructed to identify the signal outputted from the detecting means with the signal for setting the driving condition when the starting switch is actuated in certain situations. In this case, the electric signal outputted from the detecting means is identified with the electric signal for setting the driving condition. Therefore, because actuation of the starting switch controls the distinguishing operation, a separate distinguishing means is not necessary. Further, when a particular situation occurs, the setting of above described condition by the user is not performed so that the user is prevented from inadvertently altering or changing the driving (operating) condition.
In a preferred embodiment, the detecting means may include a material that can detect physical information without touching the detecting means. If the physical information is detected without touching the detecting means, the possibility for generating an inappropriate electric signal by the detecting means during operation is minimized.
In another aspect of the present teachings, a display may be provided to display at least an initial driving condition set by the setting means. In this case, the person (e.g. a supervisor) who set the driving condition can confirm the driving condition by viewing the display. Therefore, errors in setting the driving condition can be avoided. Preferably, the display is provided on a remote control device or other external device that can be utilized to program the power tool. However, the display also may be provided on the power tool.
In another aspect of the present teachings, a memory may be utilized to store a driving condition setting program that can be utilized to set the desired driving (operating) condition. A switch or other starting (actuating) means may be utilized to start the driving condition setting program stored in the memory in an appropriate situation. A setting means may be provided to set the driving (operating) condition by responding to an electric signal outputted from the detecting means in accordance with the program for setting the driving condition when the driving condition setting program starts. In this case, the driving condition setting program is started at an appropriate time by the starting means and the driving condition is set to respond to the electric signal outputted from the detecting means in accordance with the driving condition setting program. Therefore, a mechanical switch is not necessary and the driving condition setting program is not started unless a particular condition occurs. Therefore, the driving condition can not be inadvertently altered during operation.
In another aspect of the present teachings, the detecting means may comprise a sound sensor that is particularly sensitive to the particular frequency range of the impact sounds. In addition, the sound sensor is preferably relatively insensitive to sounds outside the frequency range. Thus, due to the selective sensitivity of the sound sensor, the sound sensor attenuates noises generated by the motor or other components in the power tool, as well as reflected noises, such as reflected impact sounds. By reducing the effect of irrelevant sounds detected by the sound sensor (i.e. motor noises, reflected noise, etc.), the impact sounds can be monitored more precisely. By utilizing a sound sensor adapted to more precisely detect impact sounds generated, e.g., when the hammer strikes the anvil, the precision of the torque applied to the workpiece can be increased.
In a preferred embodiment of the present teachings, the sound sensor utilized for an impact power tool may preferably comprise a piezoelectric material and more preferably, a piezoelectric ceramic material. Such materials have a selective sensitivity to a narrow frequency range and therefore, such materials are advantageously utilized with the present teachings. More preferably, the sound sensor may preferably include a piezoelectric buzzer. Such buzzers are ordinarily utilized to emit a sound within a very narrow frequency. Thus, such buzzers are not utilized as microphones, because the buzzer selectively converts electric signals into sounds within a selective and narrow frequency range. However, such piezoelectric buzzers are particularly advantageous with the present teachings, because the relevant frequency range (i.e. the hammer impact sound or an oil pulse sound) is very narrow. By appropriately selecting a piezoelectric buzzer having a peak frequency range that is approximately equal to the impact sounds, the buzzer can reliably generate electric signals for processing by the processor. Moreover, buzzers are typically inexpensive parts and thereby permit the power tools to be manufactured at a relatively low cost.
In another aspect of the present teachings, the sound sensor may be a sound detecting means having a receiver adapted to convert sounds in a selected frequency range into an electric signal. That is, the sound detecting means selectively generates electric signals based upon impact sounds, but does not generate electric signals based upon other noise generated by the power tool. A processor, such as a microprocessor or CPU, may monitor the electric signals generated by the sound detecting means and count the number of impact sounds. Based upon the number of impact sounds that are counted, the processor can control the hammer drive source (e.g. a motor) to ensure that the appropriate torque is applied to the tightened object.
Because the sound sensor has an increased sensitivity to sounds within a selected frequency range, electric signals generated by the sound sensor, due to frequencies outside the selected frequency range, are substantially reduced or eliminated. Therefore, the hammer impact sounds can be detected more reliably.
In another aspect of the present teachings, the selected frequency range of the sound sensor may be preferably adjusted to include the peak frequency of the impact sound. Although various hammers and anvils will have different frequencies due to differences in the materials utilized to manufacture these components and the manner in which the hammer strikes the anvil, the peak frequency range is generally between about 3.6 kHz to 4.4 kHz and the peak frequency is about 4 kHz.
These aspects and features may be utilized singularly or in combination in order to make improved tightening tools, including but not limited to impact wrenches and impact screwdrivers. In addition, other objects, features and advantages of the present teachings will be readily understood after reading the following detailed description together with the accompanying drawings and the claims. Of course, the additional features and aspects disclosed herein also may be utilized singularly or in combination with the above-described aspects and features.